
  <!DOCTYPE html>
  <html lang="en">

  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>

  <body>
    <div id="app"></div>
    <br />
    <div id="app1"></div>
    <script src="../js/babel.min.js"></script>
    <script src="../js/react.development.js"></script>
    <script src="../js/react-dom.development.js"></script>
    <script type="text/babel">
    class Demo extends React.Component {
      state = { date: new Date() }
    
      componentDidMount() {
        setInterval(() => {
          this.setState({ date: new Date() });
        }, 1000);
      }
    
      render() {
        return (
          <div>
            <h1>diff DOM</h1>
            <h2>new Date = {this.state.date.toTimeString()}</h2>
          </div>
        );
      }
    }
    ReactDOM.render(<Demo />, document.getElementById("app"));
    </script>
  </body>

  </html>
